In many industrial applications, rapid robotic replacement of a first magnetic data disk or a first optical data disk with a second data disk is an important concern in the design of disk drives. For example, in quality control testing associated with manufacture of magnetic and optical data disks, rapid robotic replacement increases product throughput. Placement of a data disk on a drive involves three aspects--disk introduction, centering and clamping. U.S. Pat. Nos. 4,125,883 to Rolph, 4,232,870 to Iemenschot and 4,171,531 to Grapes et al. disclose devices which both center and clamp recording media disks. The clamping devices include cylindrical members which enter a mounting aperture in the center of a disk from a direction above the disk. The periphery of the cylindrical member frictionally contacts the mounting aperture to center the disk for rotation about a vertical axis.
Because of the associated centrifugal force and because it is desirable to quality test data disk under the same conditions as will be experienced in actual use, top-clamping devices such as those noted above are preferred. Such top-clamping devices, however, require "two-handed" robotics, one hand controlling the top-clamping device and the other handling the disk. This two-handed process increases the expense of the robotic apparatus and increases the time of the robotic disk-replacement procedure.
An even more important consideration in the design of apparatus for clamping data disks involves minimalization of disk distortion. Typically, this distortion is a result of non-uniform loading pressure from a plurality of elements of a clamp device. For example, it is common to employ a plurality of elements, each of which applies a clamping force about the inner portion of the top surface of a loaded data disk. Any variance in manufacturing quality or any undesired deflections can cause wide variances in unit loading pressure. Often, a clamp device is manufactured by machining a single blank and then cutting the blank into a plurality of segments which are spaced apart as the clamp device is pressed onto the inside edge of the data disk. A variation of 0.0001 inch in the thickness of the blank can render a clamp unusable. Because of these exacting tolerances, the sequential order of the blank segments must be maintained throughout the life of the clamp. Moreover, as the segments are pushed onto the top surface of the data disk, there may be a rotation of the segments, in which case only the edges of the segments provide the loading pressure. Such rotation results in an unequal distribution of clamp force applied to only a limited number of pressure regions.
It is an object of the present invention to provide a spindle clamp which applies a substantially even clamping force for securing a magnetic or optical data disk and which permits "one-handed" robotic removal of the disk.